Pathogenesis of atherosclerosis involves multiple mechanisms, including imbalanced lipid metabolism, disturbed equilibrium of the immune response, and chronic inflammation of the artery wall. Several reports have shown a relationship between the development of atherosclerosis and the presence of infectious diseases, widely occurring in the general population, often chronic and/or asymptomatic. Beyond Chlamydia pneumoniae, a large number of infectious agents have been linked with an increased risk of vascular disease, with variable strength of supporting data: Porphyromonas gingivalis, Helicobacter pylori, influenza A virus, herpes virus, hepatitis C virus, cytomegalovirus, and human immunodeficiency virus. Infections may contribute to atherosclerosis either via direct infection of vascular cells or via the indirect effects of cytokines or acute phase proteins induced by infection at “nonvascular” sites. More recently, investigators reported that the aggregate burden (“infectious burden”) of these chronic infections, rather than the effects of a single organism, might contribute to atherosclerosis and its thrombotic complications. However, the role of infection, as a proinflammatory cause of atherosclerosis, is still debated in the literature. This article will review available data suggesting a relationship between different infective pathogens and atherothrombosis, the hypothesized mechanisms, and the potential role for antimicrobial treatment.